Feasibility and Acceptability of Using Wireless Limited Polysomnography to Capture Sleep Before, During, and After Hospitalization for Patients With Planned Cardiothoracic Surgery

BACKGROUND

Sleep disruption, a common symptom among patients requiring cardiovascular surgery, is a potential risk factor for the development of postoperative delirium. Postoperative delirium is a disorder of acute disturbances in cognition associated with prolonged hospitalization, cognitive decline, and mortality.

OBJECTIVE

The aim of this study was to evaluate the feasibility and acceptability of using polysomnography (PSG) to capture sleep in patients with scheduled cardiothoracic surgery.

METHODS

Wireless limited PSG assessed sleep at baseline (presurgery at home), postoperatively in the intensive care unit, and at home post hospital discharge. Primary outcomes were quality and completeness of PSG signals, and acceptability by participants and nursing staff.

RESULTS

Among 15 patients, PSG data were of high quality, and mean percentage of unscorable data was 5.5% ± 11.1%, 3.7% ± 5.4%, and 3.7% ± 8.4% for baseline, intensive care unit, and posthospitalization measurements, respectively. Nurses and patients found the PSG monitor acceptable.

CONCLUSIONS

Wireless, limited PSG to capture sleep across the surgical continuum was feasible, and data were of high quality. Authors of future studies will evaluate associations of sleep indices and development of postoperative delirium in this high-risk population.

An approach for determining the reliability of manual and digital scoring of sleep stages

STUDY OBJECTIVES

Inter-scorer variability in sleep staging is largely due to equivocal epochs that contain features of more than one stage. We propose an approach that recognizes the existence of equivocal epochs and evaluates scorers accordingly.

METHODS

Epoch-by-epoch staging was performed on 70 polysomnograms by six qualified technologists and by a digital system (Michele Sleep Scoring [MSS]). Probability that epochs assigned the same stage by only two of the six technologists (minority score) resulted from random occurrence of two errors was calculated and found to be <5%, thereby indicating that the stage assigned is an acceptable variant for the epoch. Acceptable stages were identified in each epoch as stages assigned by at least two technologists. Percent agreement between each technologist and the other five technologists, acting as judges, was determined. Agreement was considered to exist if the stage assigned by the tested scorer was one of the acceptable stages for the epoch. Stage assigned by MSS was likewise considered in agreement if included in the acceptable stages made by the technologists.

RESULTS

Agreement of technologists tested against five qualified judges increased from 80.8% (range 70.5%-86.4% among technologists) when using the majority rule, to 96.1 (89.8%-98.5%) by the proposed approach. Agreement between unedited MSS and same judges was 90.0% and increased to 92.1% after brief editing.

CONCLUSIONS

Accounting for equivocal epochs provides a more accurate estimate of a scorer's (human or digital) competence in scoring sleep stages and reduces inter-scorer disagreements. The proposed approach can be implemented in sleep-scoring training and accreditation programs.

Contribution of obstructive sleep apnea to disrupted sleep in a large clinical cohort of patients with suspected obstructive sleep apnea

STUDY OBJECTIVES

The response of sleep depth to CPAP in patients with OSA is unpredictable. The odds-ratio-product (ORP) is a continuous index of sleep depth and wake propensity that distinguishes different sleep depths within sleep stages, and different levels of vigilance during stage wake. When expressed as fractions of time spent in different ORP deciles, nine distinctive patterns are found. Only three of these are associated with OSA. We sought to determine whether sleep depth improves on CPAP exclusively in patients with these three ORP patterns.

METHODS

ORP was measured during the diagnostic and therapeutic components of 576 split-night polysomnographic (PSG) studies. ORP architecture in the diagnostic section was classified into one of the nine possible ORP patterns and the changes in sleep architecture were determined on CPAP for each of these patterns. ORP architecture was similarly determined in the first half of 760 full-night diagnostic PSG studies and the changes in the second half were measured to control for differences in sleep architecture between the early and late portions of sleep time in the absence of CPAP.

RESULTS

Frequency of the three ORP patterns increased progressively with the apnea-hypopnea index. Sleep depth improved significantly on CPAP only in the three ORP patterns associated with OSA. Changes in CPAP in the other six patterns, or in full diagnostic PSG studies, were insignificant or paradoxical.

CONCLUSIONS

ORP architecture types can identify patients in whom OSA adversely affects sleep and whose sleep is expected to improve on CPAP therapy.

Sleep architecture based on sleep depth and propensity: patterns in different demographics and sleep disorders and association with health outcomes

Study Objectives

Conventional metrics of sleep quantity/depth have serious shortcomings. Odds-Ratio-Product (ORP) is a continuous metric of sleep depth ranging from 0 (very deep sleep) to 2.5 (full-wakefulness). We describe an ORP-based approach that provides information on sleep disorders not apparent from traditional metrics.

Methods

We analyzed records from the Sleep-Heart-Health-Study and a study of performance deficit following sleep deprivation. ORP of all 30-second epochs in each PSG and percent of epochs in each decile of ORPs range were calculated. Percentage of epochs in deep sleep (ORP < 0.50) and in full-wakefulness (ORP > 2.25) were each assigned a rank, 1–3, representing first and second digits, respectively, of nine distinct types (“1,1”, “1,2” … ”3,3”). Prevalence of each type in clinical groups and their associations with demographics, sleepiness (Epworth-Sleepiness-Scale, ESS) and quality of life (QOL; Short-Form-Health-Survey-36) were determined.

Results

Three types (“1,1”, “1,2”, “1,3”) were prevalent in OSA and were associated with reduced QOL. Two (“1,3” and “2,3”) were prevalent in insomnia with short-sleep-duration (insomnia-SSD), but only “1,3” was associated with poor sleep depth and reduced QOL, suggesting two phenotypes in insomnia-SSD. ESS was high in types “1,1” and “1,2”, and low in “1,3” and “2,3”. Prevalence of some types increased with age while in others it decreased. Other types were either rare (“1,1” and “3,3”) or high (“2,2”) at all ages.

Conclusions

The proposed ORP histogram offers specific and unique information on the underlying neurophysiological characteristics of sleep disorders not captured by routine metrics, with potential of advancing diagnosis and management of these disorders.

0731 What is HSAT Missing? A Comparison of Respiratory Events and OSA Diagnosis Across Type 2 and Type 3 Studies

Introduction

The need for having in-home sleep testing has grown due to the COVID-19 pandemic. While Type 3 Home Sleep Apnea Tests (HSAT) are frequently used, their accuracy remains questionable. This study aimed to compare respiratory events and diagnosis of obstructive sleep apnea between Type 2 and Type 3 studies.

Methods

550 participants completed overnight Type 2 sleep studies using the Cerebra Sleep System. Files were autoscored as a type 2 acquisition and were manually edited by a RPSGT. On a second auto-score, mapped file channels were reduced to nasal cannula, chest belt, SpO2, position, heart rate, and audio channels to simulate a Type 3 study. The respiratory disturbance index (RDI) in the Type 2 tests was compared to the apnea-hypopnea index (AHI) in the simulated Type 3 files using a 4% desaturation threshold. Diagnosis of severity of OSA was classified based on indices of &lt;5 as “None”, 5-14.99 as “Mild”, 15-29.99 as “Moderate”, and above 30 as “Severe”.

Results

5 records were removed for having a TST &lt;4 hours. Type 2 sleep tests detected significantly more respiratory events (21.0±21.2/hr.) compared to Type 3 tests (13.4 ±17.2; t(549) = 26.8, p&lt;.0001). The use of the Type 2 RDI resulted in 104 patients (18.9% of patients; 39.4% of treatable patients) with moderate OSA falling into the mild category under the Type 3 AHI. The number of treatable patients was thus 71% higher with a Type 2 study. Overall, the diagnoses of Type 2 RDI and Type 3 AHI were only in agreement for 263 out of the 550 records, or 47.8% of the time.

Conclusion

The use of a Type 2 study detected more respiratory events than the Type 3 device. Consequentially, 104 patients received a higher severity of obstructive sleep apnea when the EEG information was included. Our results provide support for the use of Type 2 devices for in-home detection of obstructive sleep apnea to provide more accurate diagnostic detection than the more frequently used Type 3 home sleep apnea tests.

Support (If Any)

 

0606 A Paradigm for Testing the Accuracy of Digital Sleep Staging Systems

Introduction

Despite evidence showing that agreement between human and some automatic staging systems is generally comparable to agreement between human scorers, automated scoring is rarely used in clinical practice, even though it offers time savings and consistency. We propose a paradigm for testing digital systems that reveals their true accuracy vs. highly experienced academic scorers. As an example of a digital method to be tested, we used Michele Sleep Scoring (abbreviated:Digital).

Methods

70 PSGs were scored by 6 experienced technologists from 3 academic centers. Staging results were compared to digital staging results using an epoch-by-epoch approach. For each PSG we carried out 6 cycles of comparisons. Each cycle consisted of two steps, one comparing one scorer (tested scorer) with the scoring of the five remaining scorers (judges), and one comparing Digital as the tested scorer with the same 5 judges. Error 1 was assessed when all judges disagreed with the tested scorer but there was disagreement between the judges. Error 2 was assigned when all judges disagreed with the tested scorer but agreed unanimously on the stage. For each PSG the number of epochs with types 1 and 2 errors was counted for each scorer (n=6 scorers) and for Digital. Results of all 70 PSGs were pooled, and percent of types 1 and 2 errors is reported for all scorers and Digital.

Results

70 PSGs (females aged 51.1 ± 4.2 years) were evaluated. Average times in different sleep stages (manual scoring) were 43±18, 244±47, 30±21, and 81±25 minutes for stages N1, N2, N3 and REM, respectively. TST was 398±52 minutes, and sleep efficiency was 84±8%. There was a total of 65,053 epochs scored by each scorer and Digital. The average percent of type 1 errors made by scorers for all epochs was 6.4% (0-33.2) vs. 7.8% (1.68-26.6) made by Digital. The average percent of type 2 errors made by scorers for all epochs was 3.9% (0-28.6) vs. 4.3% (0-17.3) made by Digital.

Conclusion

This study provides an objective way of testing the accuracy of automated scoring systems and supports evidence that the accuracy of Michele Sleep Scoring is comparable to manual scoring.

Support (If Any)

None

0417 Odds Ratio Product reveals distinct sleep phenotypes in idiopathic hypersomnia

Introduction

The pathophysiology of idiopathic hypersomnia with long sleep times (IH) remains an enigma. Alternate methods to characterize sleep such as the Odds Ratio Product (ORP), a continuous measure of sleep depth, has the potential to improve understanding of IH.

Methods

The Odds ratio product is a continuous measure of sleep depth and propensity ranging 0 (very deep sleep) to 2.5 (Least sleep propensity). The difference between 2.5 and ORP in any epoch indicates extent of wake suppression (sleep depth) for that epoch. The cumulative sleep index (CSI) is the integral of sleep suppression across recording time thereby reflecting both the duration and depth of sleep over specified intervals (higher value is deeper and longer sleep). 36 patients with long sleep (600 minutes or longer) recorded through unconstrained polysomnography were analyzed using ORP across the full study (12.7±1.7 hours). Participants were divided into quartiles, 9 patients each(Q1-Q4) based on accumulated sleep across the entire study.

Results

The mean age for the cohort was 35.8 ± 16.2, of which 29/36 were females. Total sleep time by visual scoring was 679.4 ± 96.4 minutes (range: 601.5 - 1145) minutes). The whole night CSI mean was 989.39 ± 271.64 units (range: 345 to 1427). The quartile values were 618.33 ± 178.83, 919.33 ± 67.27, 1142.89 ± 39.01, and 1277 ± 69.39 units, and not related to total recording or sleep time. The NREM sleep ORP was 1.43± 0.32, 1.06 ± 0.22, 0.73± 0.13 and 0.67 ± 0.19, respectively. This distribution was true for REM sleep ORP also: 1.52 ± 0.30, 1.26 ± 0.19, 1.05 ± 0.25, and 0.84 ± 0.21, respectively. The trait-like ORP-9 (9 seconds post-arousal), and a reflection of sleep fragmentation propensity, was also similarly distributed: 1.60 ± 0.30, 1.29 ± 0.27, 0.92 ± 0.15, and 0.80 ± 0.18, respectively. All comparisons were statistically significant by Tukey multiple comparisons.

Conclusion

Patients with IH are not homogenous, showing a range of sleep depth in both NREM and REM sleep regardless of total sleep time. These phenotypes of IH could reflect unique endotypic mechanisms, requiring different therapies or have differential treatment responses.

Support (If Any)

 

0354 The Feasibility of Research Using In-Home Polysomnography for 20 Nights Across 25 Days

Introduction

Several studies have studied sleep with polysomnography (PSG) in the laboratory across multiple days but there is a paucity of research using lab-quality PSG in the home where the sleep environment is much different. In this study, we assessed the feasibility of conducting research while recording PSG in the home across multiple nights under real-world conditions.

Methods

Twenty-one participants volunteered to participate in the study and wore in-home PSG using the Cerebra Sleep System which used gel electrodes to record EEG, EOG, EMG, ECG, and a chest effort belt for 20 nights across 25 days. Participants completed baseline questionnaires (pre – and post-study), daily activities, sleep disturbances, and any skin sensitivities via online morning and evening questionnaires.

Results

Eighteen participants (age 40.2±10.5; 9 females) completed at least 18 nights of recordings and were included in the final analysis. PSG was recorded for 375 nights with an average of 20.1 nights (±3.5) recorded per participant across 24.3 days (± 2.9). Three participants withdrew from the study due to a change in work schedule (3 nights), skin sensitivity issues (5 nights), and lack of motivation (10 nights). There were 100% completion rates for questionnaires at baseline, 98% completion rates for morning questionnaires, and 93% completion rates for evening questionnaires. Participants reported skin sensitivities on 36.4% of the nights but were typically not reported again at the evening session. When there was a complaint, most of the irritations were minor with 27.1% having residual stickiness from the electrodes, 26.1% redness, and 17.5% imprints. For more of the major complaints, they were less common with 5% reporting soreness or irritation and 3.3% swelling.

Conclusion

We found that data collection from electronic questionnaires was good. Skin irritations were reported about a third of the time but typically went away across the day. These results highlight the feasibility of doing research using in-home PSG for multiple nights and the utility of collecting electronic questionnaire data for in-home research.

Support (If Any)

 

0439 A Polysomnographic Marker of Sleep Quality using Odds Ratio Product are Associated with Insomnia Symptoms in a Dose-Response Relationship

Introduction

Insomnia is primarily diagnosed with subjective complaints because objective biomarkers are limited. In the current study, we assessed whether a polysomnographic marker of sleep quality (odds ratio product; ORP) was associated with different types of insomnia symptoms.

Methods

416 participants (age 46.2±12.5; 176 females) recorded their sleep with an in-home Type 2 PSG test using the Cerebra Sleep System and filled out sleep questionnaires. Sleep quality was measured using odds ratio product (ORP) derived from frontal EEG channels across the duration of the recording (ORPTRT). On the questionnaires, participants reported whether they experienced any of the following insomnia symptoms at least three times a week: trouble falling asleep, trouble staying asleep, and waking up earlier than desired. Participants were then classified based on the total number of insomnia symptoms reported. An ANOVA, controlling for age, was performed to compare the effect of the number of insomnia symptoms on ORP.

Results

199 participants reported no insomnia symptoms, while the remaining 217 reported at least one symptom three nights a week (1 symptom: n = 62, 2 symptoms: n = 83, 3 symptoms: n = 70). There was a significant effect of number of insomnia symptoms on ORPTRT F(3,414)=3.45, p =.017. There were significant differences between ORPTRT in participants who reported 0 symptoms (.991±.267), and participants who reported 2 symptoms (1.11±.259) (t(282) = -3.57, p &lt;.001), and between 0 and 3 symptoms (1.13±.31 (t(269) = -3.46, p &lt;.001). Even within individuals reporting insomnia symptoms, there were significant differences in ORPTRT between participants who reported 1 and 2 symptoms (p=.024), and 1 and 3 symptoms (p=.029).

Conclusion

The more insomnia symptoms that were reported, the greater the impairment in sleep quality using ORP were found. Further research could explore if treatment interventions aimed at reducing ORPTRT might be useful to help treat insomnia.

Support (If Any)

 

The Odds Ratio Product (An Objective Sleep Depth Measure): Normal Values, Repeatability, and Change With CPAP in Patients With OSA

STUDY OBJECTIVES

The Odds Ratio Product (ORP) is an objective measure of sleep depth using the relationships of the powers of different electroencephalogram (EEG) frequencies in a single index. The range of the ORP is 0 (deeply asleep) to 2.5 (fully awake). This investigation seeks to elucidate normal values of non-rapid eye movement ORP (ORP_NR) in healthy individuals, repeatability of the measure, and the change in ORP_NR following continuous positive airway pressure (CPAP) treatment.

METHODS

Healthy individuals underwent a home sleep apnea test (HSAT) with EEG followed 1 week later by EEG alone. Another cohort with OSA underwent baseline HSAT with EEG followed by a second EEG study approximately 4 weeks into treatment with CPAP.

RESULTS

Thirty-eight healthy individuals completed the protocol (mean age of 34.9 ± 7.4 years, Epworth Sleepiness Scale score 3.6 ± 2.4, Insomnia Severity Index score 2.0 ± 1.6 and Functional Outcomes of Sleep Questionnaire - shorter version score 19 ± 1.2). The mean ORP_NR for all nights was 0.52 ± 0.13. The difference between the first night and the second night was 0.024 ± 0.17 (not significant). The intraclass correlation coefficient was 0.525, suggesting only moderate agreement between the first and second nights. The normal value for ORP_NR in healthy individuals is ≤ 0.78 units using two standard deviations as the cutoff. Forty participants completed the OSA protocol (mean age 49 ± 11 years, body mass index 35 ± 6 kg/m², apnea-hypopnea index 33.5 ± 28.4 events/h). The mean pre-CPAP ORP_NR was 0.69 ± 0.24 and the mean post-CPAP ORP_NR was 0.57 ± 0.22 (P = .02).

CONCLUSIONS

The ORP_NR proves to have significant variability from night to night in healthy individuals. ORP_NR objectively improves following CPAP treatment, providing further evidence that it measures sleep depth.

CITATION

Penner CG, Gerardy B, Ryan R, Williams M. The odds ratio product (an objective sleep depth measure): normal values, repeatability, and change with CPAP in patients with OSA. J Clin Sleep Med. 2019;15(8):1155-1163.